A row planter is an agricultural machine that, when pulled by a tractor, opens a furrow in the soil, places seeds at appropriate spaced intervals in the furrow, and loosely covers the seeds with moist earth. A conventional row planter generally includes a disk for forming a furrow in the soil and a press wheel for covering each seed with moist, loosely packed earth after the seed has been deposited in the furrow.
A row unit plants a single row of seeds in a field. Conventionally, farmers pull a plurality of such row units, attached to a farm implement behind their tractors. In order to attach more than one row unit to the tractor, farmers generally use an elongated articulated or pivotable tool bar, which attaches to the tractor like a trailer. The individual row units are attached, at suitable spaced intervals, substantially along the entire length of the tool bar. The weight of the tool bar, and associated row units mounted thereon, is supported by wheels mounted to the tool bar at suitable positions along the length of the tool bar. The farmer uses his tractor to pull the tool bar through a field. In this way, a farmer can plant seeds in a plurality of rows simultaneously. These rows may form a path two to three times as wide as the distance between the tractor rear wheels, as the tractor operator makes a single pass through the field.
The articulated tool bar generally comprises an elongated, intermediate tool bar portion, substantially horizontally disposed relative to the ground, and a pair of wings, each of which is pivotally connected to a respective end portion of the intermediate tool bar portion. Each wing is partially rotatable, about its associated pivot, from a substantially horizontally disposed position to a substantially vertically disposed position relative to the ground. When the tool bar is lowered toward the ground, the individual disks and press wheels of each row unit make contact with the ground. Thus lowered, the tool bar is in the so-called "working position". When the tool bar and associated disks and press wheels are raised relative to the ground and the wings disposed vertically as discussed above, the tool bar is in the so-called "transport position". Typically, on commercial farm equipment, when the wings are folded up in transport position, the wing wheels remain extended.
The intermediate tool bar portion generally has at least two wheels, each of which is positioned at a respective end of the intermediate tool bar portion. In addition, each wing has a wheel, mounted along the wing underside, spaced from its associated pivot.
Conventional tool bars further include a marker device, mounted at the distal end of one of or both of the pair of wings, for forming marker furrows in the soil. See, for example, U.S. Pat. No. 3,556,226 to Brewer et al. Each marker furrow, when formed, is spaced parallel from the row-unit furrows being formed, as a farmer makes a pass through the field. After the farmer makes a U-turn to make a subsequent pass, he will generally center his tractor on the just-formed marker furrow of the prior pass to avoid overlap of row-unit furrows or the possibility of unworked areas of field (i.e., so-called "skips") forming between row-unit furrows.
Conventional row planters have depth-control means for raising and lowering the tool bar relative to the ground, and separate wing-lift means for folding the wings up into a generally upright position to reduce actual tool bar width when the tool bar is being transported through the field. Unfortunately, separate means for performing these two functions usually requires using two separate hydraulic systems, which can be costly and add unwanted bulk to an already rather complex machine. A single system which performs both of the depth-control and wing-lift functions, described above, is currently in great demand. Further, it is occasionally desirable to be able to draw the wing wheels in toward associated wing structure, when the wings are raised, to further reduce the overall implement width.